Originally Posted by CliffordK (Post 17714188)

Most of the CREE lights run on 8.4V
The most common small solar panel is 12V.

You can buy extension cords for the CREE battery packs that you could build a connector with. As far as I can tell, the battery packs come with a charger controller and an over voltage cutoff.

What I haven't tried to do is to connect a small 12V panel into an 8.4V pack. If it was lead acid, the battery pack would pull down the voltage of the panel, and the panel would raise the voltage of the battery pack. I'm not quite sure what would happen with the Lithium batteries.

Perhaps it would be ok with a small panel. How many days a week are you using it?

Originally Posted by CliffordK (Post 17715373)

Here is your CREE Extension Cord:
New Extensive Cable for CREE XM L T6 LED Headlamp Rechargeable Headlight FF | eBay

Your USB solar charger puts out about 5.5 V.
You need something that puts out greater than 8.4V.

You could wire two of those in series which would give you about 11V which would be somewhat closer than the 12V panels.

You might also consider a DC DC voltage converter. I'm not sure if the boost and buck converters are the same, but they would allow better tuning of your voltage output, and perhaps only requiring a single solar panel.

LM2596 Buck Step Down Power Converter Module DC 4 0 40 to 1 3 37V LED Voltmeter | eBay
DC DC 4 5 32V to 5 52v XL6009 Boost Step Up Module Power Supply LED Voltmeter | eBay

Oh, another calculation.
Your battery packs use four 18650 Lithium batteries.
4.2V, with 2 to 6 ah each. So, (qty 4) x (4.2v) x (4 ah) = 67.2 watt hours for full charge.

That USB charger puts out about 7W max, when pointed directly at the sun at noon (probably a bit optimistic). So, it would take at least 10 hours of peak power generation to recharge the battery from drained to full. I'd guess maybe a couple of days (which isn't too bad).

Originally Posted by noglider (Post 17718142)

I strongly suspect that a small solar panel would not provide enough power to charge the headlight's battery to any significant extent. Stuff like that may be available in a year or two but not yet. You'll need to plug this battery in, for sure. You may want to buy a spare battery and carry it for occasions when this one discharges on the road.

It's a lot of work, to my thinking. I'm super pleased with my dynamo powered systems. I only rely on battery powered headlights briefly and infrequently nowadays.

Originally Posted by rapattack (Post 17721659)

Cool what dynamo light have u got...always wondered about them

Originally Posted by noglider (Post 17721837)

See my blog post for details. The headlight is a Philips Saferide which may not be available any more. Busch & Müller makes a huge variety of dynamo powered lights, all of them excellent. Peter White sells them and so does a too-short list of bike shops in the U.S.

Originally Posted by rapattack (Post 17723904)

Cool ...looks interesting. I am not in the US. One day thats something i will consider :0)

Originally Posted by CliffordK (Post 17723945)

I think Germany requires generators by law...

Originally Posted by Athens80 (Post 17724051)

I was curious about this. The first search result I found is not from the German government, but seems reliable:

From the European Cyclists' Federation Report on "Requirements on Lighting (Light Intensity) and Reflectors of Bicycles":

Originally Posted by CliffordK (Post 17723945)

I think Germany requires generators by law, so that is where all the good generators are. I'm getting tired of constantly recharging my batteries, and will probably setup a generator shortly.

Originally Posted by noglider (Post 17724667)

I recently read that Germany loosened the law in 2013 and a generator is no longer required. The regulations of beam shape probably still remain, and countries which don't have that requirement are indirect beneficiaries of the regulation. It has resulted in a large quantity of lights being mass produced that cast a really well shaped beam.
[MENTION=199576]rapattack[/MENTION], there are two common types of generators which are also called dynamos. There is the hub generator, where the power cable comes out of the hub. And there is the sidewall generator, also called a bottle generator because of its shape. The bottle generator is bolted to the frame. The generator hub replaces a regular old hub.

Advantages to hub generators: lower noise, much lower drag and greater reliability. The bottle generator can be knocked out of alignment.

Advantages to bottle generators: lower cost, lighter weight, no drag whatsoever when not in use.

Then again, the drag of a generator hub when not in use is extremely small. In fact, I can't perceive the drag when I do use it. The drag is so small that I run my lights day and night because it doesn't hurt, and maybe it helps me be seen in the day.

Read more on Peter White's site. Even though you probably won't buy from him, it is very informative.

On one of my bikes and two of my wife's bikes, I combined an antique bottle generator with modern LED lights. It's a nice compromise. I got the generators cheap on ebay. They power the lights just fine, and modern LED lights that are intended for generator power cast really well shaped beams.

I don't know about Australian vendors, but I've had some very good luck buying generator lights from xxcycle in France.

Originally Posted by noglider (Post 17724717)

Charging while riding is much more complicated than you would imagine. There are a few gadgets you can get which will take the output of a generator and charge a battery, but the cheap ones are crappy and maybe dangerous. The good ones are surprisingly expensive. B&M makes a headlight that also provides USB charging output, but I believe you can only run the light or the charger, not both at once. And it's about $180, so it's justified only if you're going to use it a heck of a lot.

The battery on the light you bought is fairly big, and it needs a lot of charging current. To provide that much current with solar, you'd probably need panels covering the entire bike and your entire body. :) So as I said before, plug it in every night and consider getting a spare.

Originally Posted by fietsbob (Post 17724907)

Size Matters in solar panels .. and having the panel at the best angle to the Sun .

Originally Posted by noglider (Post 17724717)

Charging while riding is much more complicated than you would imagine. There are a few gadgets you can get which will take the output of a generator and charge a battery, but the cheap ones are crappy and maybe dangerous. The good ones are surprisingly expensive. B&M makes a headlight that also provides USB charging output, but I believe you can only run the light or the charger, not both at once. And it's about $180, so it's justified only if you're going to use it a heck of a lot.

The battery on the light you bought is fairly big, and it needs a lot of charging current. To provide that much current with solar, you'd probably need panels covering the entire bike and your entire body. :) So as I said before, plug it in every night and consider getting a spare.

Originally Posted by RR3 (Post 17764351)

I have small foldable solar panel that weighs 12 oz, measures 9"x6" and it puts out 10W in direct sunlight. It will charge an i-phone in 60 minutes. I have not used it on my bike because my Panasonic 3400mAH batteries provide plenty of power for an allnight ride and carrying a spare set is much easier and lighter than trying to charge on the fly.

This is the panel and battery.....Instapark® Mercury 10M Solar Panel Portable Solar Charger with Built-in Dual USB Ports for iPhone, iPad & all other USB Compatible Devices, 5200mAh Battery Pack

Originally Posted by RR3 (Post 17764431)

I dreamed about solar panels on my property but the investment recovery time is still not acceptable to me.

If I was off-grid, I would have panels, wind generation, and one other source of power. On the grid and solar just is not cost effective and I pay 21 cents per KWH.

My portable panel is more for backpacking where you would be out for many days and where you can orient to the sun for a couple hours.